Iridium plugs, a good match for the Bob Bailey TR6 Ignition System?


Daily Driving Buick V-6 Turbo's 1979 - Present
Jul 5, 2005
Since this seems to be hijacking the original Bob Bailey TR6 thread, I thought it was worth a discussion for those of us who are running with Bob's TR6 ignition module. To start out with I bought the whole sha- bang off of him, including the coil and spark plug wires.
Well since it is black Friday and Advance Auto has a 20% off coupon.... is this what I want? plugs
or this one, these are the only two that I see that are a "exact fit"

I'm running the champion/factory iron heads by the way.

Depends upon what you want from your spark plug.

I run my car hard, and read my plugs very frequently. I look for a plug which shows no detonation specs and a good clean color relative to my tune.

Usually just about any plug will work fine for just "driving around".

At high boost and high power, I would expect a regular off the shelf spec plug to show some issues if you look close enough. That's where a racing plug makes a difference. Perhaps if the iridium plugs were made in a "racing" version with a variety of heat ranges it would be something of interest for me.

The 1st link in my thread is the "Xtreme Performance Iridium Enhanced @ Gap .035"
Looks like the heat range are not negotiable, but if we can live with "G13" heat range....
I run my car on the street, hardly ever at the track, but I run it hard enough to need a tranny with many upgrades, the stock tranny with a shift kit lasted about 2 weeks after I put the last built motor in.

Heat range needs will vary greatly from one user to another. Depends upon how the engine is setup and tuned.

When I go to the track I'll step the plugs down 1 heat range, then go back up afterwards.
Heat range chart
Picked up a TR6 a month or so ago and have been running Denso Iridium ITf20's. Actually installed them back in 2002-03. When I got back to working on the car, pulled them, gapped them and they have been fine ever since. It pulls with no issues at 25psi+.